Nature constructs three-dimensional objects with ease and out of a seemingly unlimited variety of materials with limitless geometries and scales. From prehistoric times to the present people have come up with innumerable ways of constructing physical things. One of the most ubiquitous methods of making things created in the twentieth century is injection molding. Injection molding has a number of advantages. It is a mass production process and can produce parts cheaply and quickly. It can use a large number of thermoplastic materials and produce durable lightweight parts. It does have a number of problems and limitations. The tools for injection molding are expensive and take a long time to make, on the order of months. In addition often the molds do not work correctly when first used and have to be modified. The molds wear out and cause flash. The parts shrink and warp. After repeated use molds often break or wear out. Because of the limitation of injection molding there are many restrictions in the geometry of parts that can be produced. Undercuts and other kinds of geometries that cannot be removed from a press cannot be made. This leads to assembly of multiple parts. Objects with moving parts generally cannot be built. In addition it is very difficult to decorate parts when they are molded. The process is limited to the use of polymers and the use of high performance polymers like PEEK is very difficult and injection molding cannot produce true composite parts.
Present conventional additive manufacturing technologies (e.g., 3D printing) also have a number of problems. These include slow production times, poor material properties, and limited material selection. For all of these reasons there is a long felt need to improve the process by which three-dimensional objects are made.
Printing technologies on the other hand can produce books extremely quickly at low cost and have hundreds of years of improvement in their methods. In particular, lithography, flexography, gravure and waterless printing and silkscreen (among others) are mature fast technologies that can mass-produce products at great speeds and low costs. Books, magazines and newspapers are produced quickly and cheaply. The cost of making plates is very inexpensive and the process is quite quick. There is also well-developed technology related to folding and cutting.
Every page of a book is potentially different and the technology to produce such books is widely available. This can be true even when every sheet that comes off a printer from which the pages are made can be identical to one another.
Offset lithography is a particularly mature and suitable technology for mass production of paper items—maps, newspapers, packaging and books. As with all lithography from the past two hundred years, offset lithography relies on the immiscibility of oil and water. In modern offset lithography, a special polyester, mylar, metal, or paper printing plate is used. A photosensitive emulsion covers the surface of the plate. Ultraviolet light shines on the emulsion through a photographic negative, resulting in the emulsion having the “positive” image of the original source. This step can also be performed by direct laser imaging using a platesetter. A chemical process then typically removes non-image portions of the plate. The treated plate is now fixed to a roller on a printing press. Other rollers apply water, which cover the blank non-image portions. This image formed by the selectively deposited water is transferred to a blanket usually made of rubber. The blanket is now inked with an oil based ink, and the ink is deposited where there is no water. The ink is then transferred from the rubber blanket onto paper, usually through a process that sandwiches the paper between the rubber blanket roller and an impression cylinder, which creates counter-pressure. As a result, the printed sheet also has the “positive” of the original source image, just as the photoemulsion lithography plate did.